Abstract: In a four-wheeled vehicle, the rear wheels are turned as well as the front wheels in response to operation of the steering wheel. The rear wheel turning angle characteristics relative to the front wheel turning angle is changed according to the vehicle speed. In the low to high vehicle speed region, the rear wheel turning angle is increased with increase of the front wheel turning angle and the increasing rate is increased as the vehicle speed increases. In the very low vehicle speed region, the rear wheels are not turned until the front wheels are turned at least by a predetermined angle, and are turned in the direction opposite to the front wheels when the front wheels are turned by an angle larger than the predetermined angle. The rear wheel turning angle in the opposite direction is changed in proportion to the front wheel turning angle.